linux-kernel - Re: linux interprets an fcntl int arg as long

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Message-ID: <Y2EVx95XUEVOn7p3@arm.com>
Date:   Tue, 1 Nov 2022 12:49:11 +0000
From:   'Szabolcs Nagy' <szabolcs.nagy@....com>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     Theodore Ts'o <tytso@....edu>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: linux interprets an fcntl int arg as long

The 11/01/2022 12:19, David Laight wrote:
> From: 'Szabolcs Nagy' <szabolcs.nagy@....com>
> > SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
> > {
> 
> That is just a wrapper and calls do_fcntl().
> which needs changing to be add:
> 	arg &= ~0U;
> before the switch(cmd) {

this makes sense.
i thought previously you meant masking in userspace.

although if you mask there then many linux internal
apis could use int instead of long arg.

do you want me to post a patch? (i'm not a kernel
developer)